Johnson is a candidate to replace Chris Sale (elbow) for Tuesday's start, but Boston has yet to make an official announcement, Ian Browne of MLB.com reports.
The Red Sox's rotation is in flux at the moment, and they need a starter Tuesday. Johnson and Andrew Cashner are possible candidates. David Price (wrist) is expected to rejoin the rotation this week but may not be ready in time for Tuesday's game. Going forward, Johnson could pick up a start every fifth day, joining Price, Eduardo Rodriguez, Nathan Eovaldi and Rick Porcello.